| Energy and environmental issues have been the concern of human beings. To meet the growing energy needs while avoiding the depletion of resources and environment damage, lithium-ion batteries (LIBs) and photocatalytic technology came into being. Transition metal oxides (TMOs) play a very important role in the field of energy storage and conversion and light catalysis. In this paper, nano-engineering was used as modified means. Starting from the material micro-and nano-structure design, we successfully prepared 3D hierarchical porous NiO nanoflowers and metal-organic frameworks (MOFs) derived Fe2O3/C nanoshuttles. Then, electrochemical measurements and photocatalytic properties were conducted using NiO, Fe2O3/C as active materials, respectively. In this paper, we aim to provide a useful exploration for choosing proper materials for LIBs and photocatalysis.1.3D Hierarchical Porous NiO Nanoflowers as an Advanced Anode Material with Remarkable Lithium Storage PerformanceWe synthesized 3D hierarchical porous NiO nanoflowers with a two-step hydrothermal-calcination method. The phase and microstructure of NiO nanoflowers has been characterized in detail by means of XRD, FE-SEM and TEM. Microstructure analysis shows that the 3D NiO nanoflower consists of porous NiO nanosheets which are composed of nanocrystals with particle diameter of about 15 nm. These 3D porous NiO nanoflowers, used as lithium-ion battery anode material, exhibit excellent electrochemical performance. The capacity retention of the product is remarkable. Surprisingly, a capacity higher than 1100 mAh g’1 is retained in the initial 20 cycles and a capacity of ca.845 mAh g"1 can be perfectly maintained even after 50 cycles. Even at the rate as high as 1000 mA g"1, a capacity of 380 mAh g’1 can still be delivered, which is comparable to the theoretical capacity of graphite (ca.372 mAh g"1). The results indicate that the NiO nanoflowers could be an ideal anode material with excellent cycle stability and rate capability.2. MOFs-Template Derived Porous Fe2o3/C Nano-shuttles as Anode Material for High Performance Lithium-Ion BatteriesA direct one-step coprecipitation route was adopted for the synthesis of Fe-MIL-88B MOF precursor, and then Fe2o3/C nano-spindles were formed by calcination of Fe-MIL-88B precursor. By FE-SEM and TEM microstructure analysis, we can see that these nano-shuttles are almost identical with a length of about 1.5 um, and width of 500 nm. The uniform-sized product shows good dispersibility, with each Fe2o3/C nano-shuttle composed of many small nanocrystals. These nanocrystals play an important role in the photocatalytic tests, which can increase the surface area of the material, enhance the adsorption of the dye molecules. In addition, MOFs-derived Fe2o3C composite can quickly transfer light-generated electrons to prevent recombination between photo-generated electrons and holes, thereby incresing the photo-carrier concentration and thus the photocatalytic efficiency can be improved. The prepared porous Fe2o3/C nanoshuttles were used as a catalyst for the degradation of methylene blue (MB) solution under simulated sunlight illumination. The results show that MB degradation rate reached 85.2%with light time of 210min, much higher than thar of commercial Fe2o3 and Fe2o3 nanoshuttles calcinated under air (only 20%and 24.4%). |
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